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A163559 Composite numbers such that exactly seven distinct permutations of digits give primes. 3

%I #4 Apr 16 2013 19:59:49

%S 1037,1073,1190,1247,1274,1345,1354,1370,1379,1397,1435,1472,1495,

%T 1534,1594,1679,1703,1724,1730,1739,1742,1769,1793,1796,1910,1937,

%U 1945,1954,1967,1976,2093,2147,2174,2374,2390,2471,2597,2714,2734,2743,2759,2795

%N Composite numbers such that exactly seven distinct permutations of digits give primes.

%e a(1) = 1037 because 1037 is composite and 137, 173, 317, 1307, 3701, 7013, and 7103 are prime permutations, and no other permutation of 1036 is prime.

%t Select[Range[3000],!PrimeQ[#]&&Count[Union[FromDigits/@ Permutations[ IntegerDigits[ #]]], _?PrimeQ]==7&] (* _Harvey P. Dale_, Apr 16 2013 *)

%K easy,nonn,base

%O 1,1

%A _Gil Broussard_, Jul 30 2009

%E Example moved from Maple field to Example field by _Harvey P. Dale_, Apr 16 2013

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Last modified August 15 14:50 EDT 2024. Contains 375173 sequences. (Running on oeis4.)